1. Technical Field
This invention relates generally to an antenna system and, more particularly, to a high frequency multi-turn loop antenna for use on a conductive structure such as the airframe of an airborne vehicle.
2. Discussion
Many communication systems generally employ antennas for transmitting and receiving communications signals. High frequency antennas for use with airborne vehicles and the like have been employed. However, such antennas have generally been relatively large and/or have presented various operational problems.
One common high frequency airborne antenna currently in use with aircraft vehicles is a trailing wire antenna (TWA). The TWA is essentially a horizontal dipole which generally employs a weighted trailing wire that for some applications may be 140 feet or more in length. The relatively large size of the trailing wire is required to produce the necessary resonance. The trailing wire in conjunction with the airframe of the aircraft may provide the necessary length and shape for transmitting or receiving desired signals.
The TWA has been developed into a relatively efficient antenna, however, various undesirable operational problems do exist. Such problems include decreased maneuverability of the aircraft due to the external wire. In addition, it is generally required that the trailing wire of the TWA must be fully secured for aircraft landing. Other problems have included reliability and safety issues which have arisen with respect to the trailing wire extension and retraction mechanism. Furthermore, the relatively high rate of mechanism failure of the TWA and the circuitry of the explosive "guillotine" for purposes of severing the TWA when necessary have demonstrated a somewhat poor reliability.
Another high frequency antenna deployed on airborne vehicles is the towel bar antenna which essentially provides a single turn loop antenna. However, the towel bar antenna is relatively large in size and does not provide the best possible efficiency.
It is therefore desirable to obtain a compact high frequency antenna for use on a conductive structure such as an airborne vehicle. More particularly, it is desirable to obtain a compact high frequency multi-turn loop antenna which may be flush-mounted or embedded within the conductive structure.